High-pressure (0.8 gigapascals) granulite facies garnet from Gore Mountain, New York, hosts multiple solid inclusions containing the low-pressure silica polymorph cristobalite along with albite and minor ilmenite. Identification of cristobalite is based on Raman spectra, electron microprobe analysis, and microthermometric measurements on the alpha/beta phase transformation. The cristobalite plu...

We study the pressure-driven phase transition from the four-coordinate wurtzite to the six-coordinate rocksalt structure in CdSe nanocrystals with molecular dynamics computer simulations. With an ideal gas as the pressure medium, we apply hydrostatic pressure to spherical and faceted nanocrystals ranging in diameter from 25 to 62 A. In spherical crystals, the main mechanism of the transformatio...

A continuum thermomechanochemical model of the behavior of a plastic-bonded explosive PBX 9501 formulation consisting of the energetic crystal octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine HMX embedded in a polymeric binder is developed. Our main focus is on the study of the ↔ phase transformations PTs in crystalline HMX under a complex pressure-temperature path. To reproduce the pressure-te...

Diffusion of organic vapours to the surface of aerosol or cloud particles is an important step for the formation and transformation of atmospheric particles. So far, however, a database of gas phase diffusion coefficients for organic compounds of atmospheric interest has not been available. In this work we have compiled and evaluated gas phase diffusivities (pressure-independent diffusion coeff...

Ab initio calculations of binary metallic systems often predict ordered compounds in contrast to empirical reports of solid solutions or disordered phases. These discrepancies are usually attributed to slow kinetics that retains metastable structures at low temperatures. The Fe-V system is an example of this phenomenon, in which we predict two ordered stable ground states, Fe3V and FeV3, wherea...

The glaciation time of a mixed-phase cloud due to the Wegener–Bergeron–Findeisen mechanism is calculated using an adiabatic one-dimensional numerical model for the cases of zero, ascending, descending and oscillating vertical velocities. The characteristic values of the glaciation time are obtained for different concentrations of ice particles and liquid-water content. Steady state is not possi...

In this study, NiTi thin films were deposited on the glass and NaCl substrates by means of magnetron sputtering method. The influence of aging temperature, over the range 300-500 oC, on phase transformation and mechanical properties of the sputtered NiTi thin films were studied by differential scanning calorimetry (DSC) and nano-indentation assay, respectively. The DSC curves showed that the ag...

There are two crystalline modifications of zinc sulphide. The high-temperature hexagonal (e) phase and the low-temperature cubic (/~) phase exhibit a reconstructive transformation at a transition temperature of about 1020 ° C. The transformation of e phase back to ~ phase is a sluggish process compared to that of/3 to :~ [1], therefore once it is formed the a phase will remain as a metastable p...

With the notable exceptions of water, ammonia and a very limited number of other examples, there have been relatively few highpressure structural studies of simple molecular compounds. Such studies can provide fascinating information about intermolecular interactions and pressure-induced phase transition, in particular hydrogen-bonding interactions. Recent results for thiourea and urea obtained...